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Bridges & Structures

Dam as a Foundation for a Highway

Formerly Federal-aid Policy Guide Non-Regulatory Supplement NS 23 CFR, Part 630H,
December 9, 1991, Transmittal 1
See Order 1321.1C FHWA Directives Management

  1. Applicability (23 CFR 630.802)
    1. Title 23 U.S.C. 320 provides for cooperation between (1) the agency of the Federal Government having jurisdiction over and custody of a Government-owned dam, either previously constructed, now under construction, or to be constructed; (2) the highway department of the State, or the appropriate subdivision thereof, in which the dam is located; and (3) the Federal Highway Administration (FHWA), in the design and construction of the dam so that it will serve as a suitable foundation for a public highway bridge, and in the construction of such a bridge.
    2. Title 23 U.S.C. 320 does not necessarily relieve an agency of the United States from any legal obligation that it may have to relocate or replace an existing bridge or road because of the construction or proposed construction of a dam by such agency.
    3. The construction of the required roadway approaches is the responsibility of the State highway agency (SHA).
    4. There are limitations as to the use of the funds provided and FHWA is empowered to make a determination as to what portion, if any, of the bridge beyond the physical limits of the masonry structure, or structures, of the dam may be financed wholly from such funds.
  2. Procedures (23 CFR 630.803)
    1. Sections 320(a), (b), and (c) of Title 23 U.S.C. prescribe the procedure to be followed in qualifying a bridge for construction with funds authorized under Section 320(d) of that Title.
    2. State Application
      1. Where the dam is located on a river forming the boundaries of two or more States, the data should be presented jointly by the States.
      2. The application and supporting data should be submitted to the Division Administrator and forwarded, through the Regional Federal Highway Administrator, to the Washington Headquarters.
    3. If FHWA finds that the proposed bridge is economically desirable and needed as a link in one of the Federal-aid systems, it will join with the SHA in so certifying to the agency having jurisdiction of the dam, and will request the agency to investigate the project to determine whether the bridge is structurally feasible and whether it can be constructed without interfering with the proper functioning of the dam.
    4. Upon receipt of confirmation, FHWA will request the agency to proceed with the design of the dam so that it will serve as a foundation for the bridge, and with the design of the bridge, with the understanding that the agency will be reimbursed from funds provided under 23 U.S.C. 320(d) for the additional engineering costs incurred.
    5. The agency will be requested to furnish copies of the completed plans, specifications, and estimates to the SHA and FHWA. 23 U.S.C. 320(e) imposes upon FHWA the responsibility for recommending standards governing the roadway design of the bridge.
    6. Before the agency having control of the dam can undertake construction of the bridge over the dam, it will be necessary for the State to enter into an agreement with that agency, and with FHWA, that the State will construct and maintain the roadway approaches or cause them to be constructed and maintained. This agreement will provide for:
      1. construction and maintenance of the bridge by the agency,
      2. conveyance of necessary rights-of-way by the agency to the State or appropriate subdivision thereof,
      3. the method and amount of reimbursement to the agency, and
      4. related matters required by 23 U.S.C. 320.
Updated: 06/27/2017
Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000